KR20060047244A - Rotary removal tool for chip removal machining - Google Patents

Abstract

The present invention comprises a rotatable body (4) and a replaceable cut or lustop (5) which can be securely connected by means of a male / female coupling to the body, the coupling comprising: a body ( A female-like groove 11 formed at the front end of 4) and defined by a bottom face 14 and two side surfaces 15 and insertable into the groove and the lustop 5 It is directed to a cutting tool of the type which projects rearward from and also comprises a male part 22 with an end face 23 and two flank faces 24. In the front part of the main body 4, there is formed a slot 12 which is opened forward, which slot is elastically deflectable to support the male part 22 clamped in the groove 11. The sheeting part 28 for separating the part 13 and accommodating the protrusion part 27 of the other surface is formed in one of the said end surface 23 and the bottom face 14. According to the invention, the seating portion 28 is more than the projection 27 so that the male portion 22 of the lustop 5 can be self-centered by moving a short distance in the groove 11. Big or wide

Chip Removal Machining

Description

ROTATABLE TOOL FOR CHIP REMOVING MACHINING}

1 is a perspective view of a cutting tool in the form of a drill according to the invention and mounted in a rotatable machine spindle, the body of which is indicated by a dashed line.

2 is an enlarged perspective view showing a part of a main body and a cutting portion or a lustop separated from the main body;

3 is a view showing an end of the main body of FIG.

4 is a view showing an end portion of the lustop of FIG. 2.

5 is a longitudinal (A-A) cross sectional view of the tool in the assembled state;

FIG. 6 is an enlarged cross-sectional view showing a portion of an interface between the lustop and the body, more precisely the protrusion region received in the seating portion, wherein the protrusion is centered with respect to the seating portion.

FIG. 7 is a cross-sectional view corresponding to FIG. 6, showing protrusions laterally displaced in the seating portion. FIG.

8 shows an enlarged view corresponding to FIG. 2, showing a second embodiment of the tool according to the invention.

9 is an enlarged view showing a third embodiment of the present invention.

10 is a side view of the main body.

11 is a view showing the end of the same main body.

12 shows the end of a lustop cooperating with the body of FIGS. 10 and 11.

It is a figure which shows the edge part of another embodiment of a lustop.

Explanation of symbols on the main parts of the drawings

1 Cutting tool 2 Holder

3 spindles and 4 bodies

5 lustops (cutting part) 11 grooves

13 foot 14 bottom

15 side 24 flank face

27 Projection 28 Seating

The present invention provides a rotary tool for chip removal or chip forming machining, comprising a main body and a replaceable cutting portion which can be securely connected to the main body by a male / female coupling, the coupling having a front end of the main body. And a female-like groove defined by the bottom face and the two side faces, and insertable into the groove and protruding rearward from the cutting portion, and having an end face and two flank faces. A male part, a front part of the body having a slot which is open forward and separates two elastically deflectable legs to support the male part clamped in the groove; It relates to a rotary tool of the type in which one of the end face and the bottom face is provided with a seating portion for receiving a projection of the other face.

Cutting tools of the type that use replaceable cutting units separate from the main body have a substantially moving shape, for example, consisting of a milling tool such as a drill tool, an end mill or a slitting cutter, a thread cutter, and the like. In general, the body consists of an elongated shaft of cylindrical basic shape. In modern machining tools, the main body is very complicated and expensive, and therefore, for economic reasons, it cannot be integrated with the cutting part, which constitutes the wear part of the tool and whose service life is limited. In other words, it is advantageous to make the actual cutting part in the form of a separable part separately, which is called "lustop" among those skilled in the art and can be replaced after being worn, while the expensive body has a longer period of time (usually lu For 10 to 20 replacements of the stop). In practice, all or part of the lustop is made of a hard wear resistant material, such as cemented carbide, but the body is made of a material having a fairly large elasticity, such as steel. It should be borne in mind that the tools of the kind mainly dealt with (but not necessarily) are for the machining of metal workpieces.

In particular, the development of lustop is required in the field of drilling. For drilling, a simple drilling machine or multi-acting machine comprising a tightly mounted machine spindle or holder is used, the rear end of the cutting tool body can be fixed, while the front end of the body is for cutting or chipping the intended workpiece. Freely available for mounting and detachment of the lustop to carry out removal. The most ideal condition is that, in order to form a hole with optimum accuracy in terms of the position and shape of the workpiece, the geometric center axis of the lustop as well as the geometric center axis of the body is exactly in line with the extension of the geometric center axis of the machine spindle. It is. However, in practice, as is known, optimum accuracy is due to the unavoidable tolerances at the interface between the main body and the lustop, which are individually manufactured from different materials through different operations, and due to the various types of defects of the main body and the lustop. Is difficult to get. In practice, therefore, it is not uncommon for the drill wobble, ie the tip of the lustop, in connection with entering the workpiece to be inadvertently located next to a straight line, which is an extension of the geometric center axis of the machine spindle, which results in a hole being formed. The geometric position of Therefore, instead of moving linearly within the workpiece to finally stabilize with a linear path of travel, a circular or planetary motion that may initially position the tip of the lustop somewhat further from the intended path of travel. motion).

Cutting tools of the type mentioned at the beginning are already known by SE 0103752-2. However, a disadvantage of this tool is that the male portion of the lustop is formed to be laterally inserted into the receiving groove of the main body. In order to eliminate this drawback, a tool was introduced in SE 0400057-8 which allows the axial insertion of the male part of the lustop into the groove of the body. In this case, the male portion of the lustop is formed to have a centering protrusion formed symmetrically in the rotational direction, which is similarly arranged to engage with the seating portion formed on the bottom of the groove symmetrically in the rotational direction. The purpose of the centering protrusion is to center the lustop relative to the body, for which the centering protrusion has a conical outer surface, the maximum and minimum diameters of which are substantially circular, defining the mouth of the seating portion. The line contact is adjusted between the edge and the protrusion. This configuration requires very good manufacturing accuracy in producing lustop from cemented carbide and in producing the body from steel. Also, even if the lustop is actually centered exactly with respect to the body, manufacturing accuracy is not guaranteed. Thus, due to a very small defect of the body, the central axis of the lustop itself can be located next to a straight line which is an extension of the central axis of the machine spindle.

The present invention aims to obviate the above disadvantages of known cutting tools and to provide improved cutting tools. It is therefore a primary object of the present invention, in particular, to provide a cutting tool for drills in which the lustop can be centered in a very accurate way with respect to the central axis of the machine spindle. Another object of the present invention is to realize improved machining accuracy by simple and inexpensive means. The nature of the interface between the lustop and the body gives the user / operator a tool that gives the user / operator a reassured feeling that the lustop can be fixed in the groove of the body in a clear and reliable manner with respect to the mounting of the lustop. It is also an object of the present invention.

According to the invention, at least said main object is achieved by the features defined in the characterizing part of claim 1. Preferred embodiments of the tool according to the invention are further defined in the dependent claims.

In FIG. 1 a cutting tool 1 in the form of a drill is mounted in a holder 2, which is mounted in a rotatable machine spindle 3. The drill consists of a body 4, indicated by dashed lines, and a cut or loose top 5, which is separable. In this case, the main body 4 consists of a relatively narrow cylindrical shaft, and at the rear end of the shaft, a thick portion 6 which can be fitted to the holder 2 is formed. The holder can be fitted to the hollow part 7 in the spindle 3. In order to transmit torque to the drill, two shoulder portions 9 are arranged on the front face of the spindle 3, which shoulder portions engage the recesses of the holder 2. The shaft 4 is formed with a spiral chip channel 10. As can be clearly seen in FIG. 1, the lustop 5 is mounted at the front free end of the shaft 4.

In FIG. 1, "C" indicates an imaginary geometric center line, which is indicated by a dashed line, extending from the rear end of the spindle 3 to the front end of the lustop 5. In practice, however, each part 2, 3, 4, 5 has its own geometric center axis. Therefore, the spindle 3 has a center axis denoted by C3, and the holder 2, the main body 4 and the lustop 5 have center axes denoted by C2, C4 and C5, respectively. For the machining precision of the tool, it is important that the center axis C5 of the lustop 5 is concentric with the center axis C3 of the spindle 3. Accordingly, it is an object of the present invention that the center axis C5 of the lustop 5 is the central axis of the spindle 3, although it is secondary whether the center axes C2 and C4 are completely concentric with the center axes C3 and C5. To ensure that it is correctly positioned on the extension of C3).

Reference is now made to FIG. 2 showing the configuration of the interface between the lustop 5 and the drill or body 4 according to the first embodiment of the invention.

A groove 11 is formed at the front end of the main body 4, and a slot 12 for separating two elastically deflectable leg portions 13 is opened in the groove. The groove 11 is defined by a bottom 14 and two sides 15, which define a jaw having a tapered shape in the shape of a wedge toward the front side (upward in the figure). In one of the legs 13 there is a hole 16 for tightening screws (not shown) which allow the legs to be deflected and somewhat separated from each other.

The lustop has a basic shape which is rotationally symmetrical, as long as the lustop 5 has a circular outer shape close to the cylinder or an outer surface 17 which is slightly conical to the rear. The front face 18 (see FIGS. 4 and 5) of the stop stop is conical and ends at the central tip 19. In general, the lustop has an outer diameter somewhat larger than the diameter of the body 4. On the outer surface 17, two concave confinement surfaces 20 are formed, which are connected to the surface 10 and define a chip channel of a stop. In the front part of the lustop, cutting edges 21 are formed adjacent to the chip channel 20, which are spaced apart from each other in the radial direction, that is, 180 degrees apart from each other at the same distance. In other words, the lustop has a symmetrical basic shape. At the rear or inner end of the lustop, a male portion 22 for engaging with the groove 11 is formed. The male part is defined by one end face 23 and two flank faces 24 which are inclined corresponding to the wedge shape of the groove determined by the inclined side 15. On both sides of the male portion 22 there is a flat axial force transfer surface 25 for cooperating with the uniform surface 26 on both sides of the groove 11.

The end face 23 of the male portion 22 is provided with a protrusion 27 engaged with the seating portion 28 in the bottom face 14 of the groove 11.

All or part of the lustop 5 is made of cemented carbide or other wear resistant material, but the body 4 is made of a material having a fairly large elasticity, such as steel. The steel is preferred because of its inherent elasticity or flexibility, which makes it possible to elastically deflect the legs 13 which are separated from each other by the slots 12.

In the tool descriptions thus far, the essential construction of the tool is already known. A known feature of the tool is that it has a shape which makes intimate contact with the seating portion when the projection 27 is inserted into the seating portion 28 such that the lustop is centered in an immovable state relative to the body.

A feature of the tool according to the invention is that the seating portion 28 is provided with a projection 27 so that the male part 22 of the lustop 5 can move reciprocally in the groove 11 to enable self-centering of the lustop. Greater than). More specifically, without stopping the central axis C4 of the main body 4 from coinciding with the imaginary extension of the axis C3 (at full length), the lustop 5 has its central axis C5 being the spindle 3. It should be able to be in the centering position to be coincident with the virtual extension line (C) of the central axis of.

In the embodiment of FIGS. 2 to 7, the protrusions 27 and the seating portions 28 have a basic shape of a rectangle. Thus, the projection 27 is formed of four flat flank surfaces 29 and a flat lower end surface 30. As can be clearly seen in FIGS. 6 to 7, the flank surface 29 is inclined with respect to the end face 23 of the male part, more specifically inclined inwards toward each other, so that the protrusions from the end face 23. Tapered in this direction. Since the seating portion 28 generally advantageously has the same shape as the protrusions, the seating portion is formed of four flat and inclined side surfaces 31 and a flat bottom surface 32. In general, however, the seating portion is larger than the protrusion. Therefore, the surface contact between the lustop 5 and the main body 4 is made only between the end faces 25, 26 and between the side face 15 of the groove and the partial flank face 24. This means that the end face 23 of the male part is separated from the bottom face 14 of the groove, as can be clearly seen in FIGS. 6 and 7. Moreover, the height of the protrusion part 27 with respect to the depth of the seating part 28 is determined so that the said surface 30 and 32 may not contact each other. In other words, the protrusion does not touch the bottom of the seating portion.

In Fig. 6, the projection 27 is located at the seating portion 28 at a neutral intermediate position, so that the two flanks 29 of the projection are separated from the side face 31 of the corresponding seating portion. The projection 27 can move reciprocally from this neutral position (defined by the reference line R) in the plane defined by the groove 11, that is, the plane flat to the side surface 15 of the groove. However, because the deflectable leg 13 guides the male portion linearly while continuing to exert a force on the flank surface 24 of the male portion 22, the protrusion cannot move perpendicular to the surface. In this regard, it should be borne in mind that the fact that the projection 27 can move in the groove 11 does not mean that the projection can move freely. In contrast, the deflectable leg 13 ensures the prestress of the protrusion at any position that the protrusion and lustop take upon mounting. Therefore, when the stop stop enters the workpiece and is subjected to significant cutting forces, the lateral displacement of the stop stop occurs first. In other words, as long as the drill rotates without entering the workpiece, the leg clamps the protrusion at any given position.

FIG. 7 shows a state in which the projection 27 is displaced to the right (after receiving a cutting force) to an end position where the right flank 29 is in contact with the right side 31 of the seating portion. The distance d at which the protrusion moves from the position in FIG. 6 to the position in FIG. 7 measures the value of the size difference between the seating portion and the protrusion. In other words, the value (d) can be regarded as defining the radial mobility of the lustop (radial mobility = 2d).

The difference between the width of the seating portion 28 and the width of the protrusions 27 which appear in the longitudinal extension of the grooves is substantially dependent on the diameter of the drill, and more clearly, the difference is small and large diameter for small diameter drills. In the case of large. In all cases, however, the difference between the width of the seating portion and the width of the projection should be 0.02 mm (d = 0.01 mm). On the other hand, the width of the seating portion should be at most 0.20 mm (d = 0.10 mm) larger than the width of the protrusion. In practice, the difference between the width of the seating portion and the width of the projection is advantageously in the range of 0.04-0.16 mm, preferably 0.07-0.13 mm.

The lustop can be moved radially within the range determined by the value 2d, allowing self-centering of the lustop upon entering the workpiece. Therefore, the central axis C4 of the main body 4 in the interface region facing the lustop is caused by the central axis of the spindle 3 due to tolerances of the interface and / or small shape defects of the main body and / or the holder 2, and the like. If it is not concentric with C3), the lustop will move to the center defined by the extending straight line of the central axis C3 of the spindle. This is done after the lustop enters the workpiece and the leg 13 receives a much greater cutting force than the prestressing force exerted on the male portion 22 of the lustop.

In the tool of FIGS. 2 to 7, the seating portion 28 is entirely located in half of the bottom face 14 (located on one side of the slot 12), and correspondingly the projection 27 is laterally displaced. have.

In FIG. 8, showing another embodiment, an elongated seating portion 28 traverses the slot 12. More specifically, the seating part in this case consists of the same two partial recesses which are open upwards and with respect to the slot 12. The width of the projection between the sides 29 is smaller than the width of the seating between the sides 31, but the projection 27 of the lustop 5 has the same elongated form as the seating 28. The seating portion and the elongate projections are oriented perpendicular to the radial direction of the motion of the lustop 5, thereby widening the contact surfaces 29, 31 which stop the lustop in the outward position.

Another difference between the embodiment described above and the embodiment of FIG. 8 is that the latter embodiment lacks a fastening screw for deflection of the leg 13. Instead, for the key having an elliptical cross section, a key groove 33 which is elliptical when viewed in cross section is formed adjacent to the slot 12, by which the legs can be bent away from each other.

Another embodiment of the invention is shown in FIG. In this case, the seating part 28 is formed in the male part 22 of the lustop 5. More specifically, the seating portion 28 has the shape of an elongated groove having a V-shaped cross section, is recessed in the end face 23 and extends over the entire width of several parts. Next, the protrusion 27 is formed in the groove of the main body 4. More specifically, the protrusion has the shape of a bulge or ridge having a V-shaped cross section and protrudes from the bottom of the groove 14. The ridge is advantageously disconnected by the slot 12 but extending over the entire width of the groove. In the above-described manner, the width of the groove 28 is larger than the width of the ridge 27 so that the male portion 22 can be reciprocally displaced over a short distance from the groove.

Reference is now made to FIGS. 10 to 13 showing how the grooves 11 of the body 4 are oriented in the face P. FIG. In figure 13 a symmetrical lustop is shown, in which two cutting edges 21 which are spaced apart at the same distance, ie opposite each other in the radial direction, are located in the radial plane EP. It is ideal to orient the male part 22 of the lustop to the face EP, but this is difficult or impossible due to the geometry / structure (depending on the formation of the chip channels 10, 20). Therefore, in general, the male part should be oriented at a constant angle α with respect to the radial plane EP. In the example of FIG. 12, this angle α, which is about 15 °, should be as small as possible and in no case exceed 30 °. The angle α is suitably smaller than 20 to 25 degrees.

13 shows another embodiment of lustop. In this case, the male portion 22 rotates clockwise with respect to the male portion of FIG. In this case, the angle α must not exceed 30 °.

The invention is not limited to the embodiments described above and illustrated in the drawings. Accordingly, the geometry of the protrusions and seating may be modified in various ways within the scope of the claims. For example, each of the protrusions and the seating portion may have a basic shape that is rotationally symmetric, such as a cylindrical or slightly conical basic shape.

According to the present invention, the lustop can be centered in a very accurate manner with respect to the center axis of the machine spindle, and improved machining accuracy can be realized by simple and inexpensive means.

Claims (8)

A main body 4 and a replaceable cutting part 5 which can be firmly connected to the main body by a male and female coupling, the coupling being formed at the front end of the main body, and also having a bottom face 14 and two A female groove 11 defined by the side surface 15, and a male portion insertable into the groove and projecting rearward from the cutting portion, and having an end face 23 and two flanks 24; 22), In the front part of the main body, there is a slot 12 which is open forward and separates the two elastically deflectable legs 13 to support the male part 22 clamped in the groove 11. Formed, In one of the end face 23 and the bottom face 14, a seating portion 28 for receiving a projection 27 on the other side is formed, the rotary tool for chip removal machining, The seating portion 28 is larger than the projection 27 so that the male portion 22 of the cutting portion 5 reciprocally moves in the groove 11 to enable self-centering of the cutting portion 5. Tool made. 2. Tool according to claim 1, characterized in that the width of the seating portion (28) is at least 0.02 mm greater than the width of the protrusion (27) when viewed in the longitudinal direction of the groove (11). The tool according to claim 1 or 2, characterized in that, when viewed in the longitudinal direction of the groove (11), the width of the seating portion (28) is 0.20 mm or less larger than the width of the protrusion (27). 4. The cutting part 5 according to any one of claims 1 to 3, wherein the cutting portion 5 includes a central tip 19 and a plurality of cutting edges 21 generally radially extending from the central tip. Tool having a symmetrical geometric shape, wherein the cutting edges are spaced at equal distances from each other. The projection 27 is formed in the end face 23 of the male portion 22, and the seating portion 28 is formed in the groove 11. A tool, which is formed on the bottom face (14). 6. Tool according to claim 5, characterized in that the entire seating portion (28) is located next to the slot (12) separating the two deflectable legs (13) of the body. 6. Tool according to claim 5, characterized in that the seating portion (28) is formed by partial recesses on both sides of the slot (12) and traverses the slot (12). 8. The seating portion and the protrusion portion have an elongated basic shape, and are respectively extended perpendicularly to the longitudinal direction of the groove 11 and the male portion 22. tool.

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